Stator, stator manufacturing method and motor

ABSTRACT

A stator includes core pieces in which at least first and second laminate members are laminated, the first laminate member includes a first tooth portion and a first core back portion, the second laminate member includes a second tooth portion and a second core back portion, the first core back portion includes a first protrusion on one side thereof in a circumferential direction and a first recess on the other side thereof in the circumferential direction, the second core back portion includes a second recess on one side thereof in a circumferential direction and a second protrusion on the other side thereof in the circumferential direction, and an area of a region in which the first and second core back portions of the core piece adjacent thereto overlap in a lamination direction is greater than a circumferential cross-sectional area of the first core back portion circumferentially inward from the first protrusion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2016-172340 filed on Sep. 2, 2016 and is a ContinuationApplication of PCT Application No. PCT/JP2017/031388 filed on Aug. 31,2017. The entire contents of each application are hereby incorporatedherein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a stator, a stator manufacturing methodand a motor.

2. Description of the Related Art

A stator of a motor includes a plurality of teeth radially installedthereon, and an annular part connecting radially outer sides of theteeth in an annular shape. In the stator, an inclined part is formed onan end portion of each core piece of each divided laminate core, andpairs of core pieces with different shapes are alternately laminatedwith one another. However, in the conventional stator mentioned above,one goal has been to mitigate concentration of magnetic flux to preventmagnetic flux saturation, and sufficient magnetic flux in a laminationdirection has not yet been obtained.

SUMMARY OF THE INVENTION

According to an example preferred embodiment of the present invention, astator includes an annular core with a center that is a verticallyextending central axis around which a conductive wire is wound, in whichthe core includes core pieces in which at least a first laminate memberand a second laminate member are laminated, the first laminate memberincludes a first tooth portion extending in a radial direction and afirst core back portion connected to a radially outer side of the firsttooth portion and extending in a circumferential direction, the secondlaminate member includes a second tooth portion extending in the radialdirection and a second core back portion connected to a radially outerside of the second tooth portion and extending in the circumferentialdirection, the first core back portion includes a first protrusionprovided on one side thereof in the circumferential direction and afirst recess provided on the other side thereof in the circumferentialdirection, the second core back portion includes a second recessprovided on one side thereof in the circumferential direction and asecond protrusion provided on the other side thereof in thecircumferential direction, and an area of a region in which the firstcore back portion and the second core back portion of the core pieceadjacent to the first core back portion overlap in a laminationdirection is greater than a circumferential cross-sectional area of thefirst core back portion circumferentially inward from the firstprotrusion.

The above and other elements, features, steps, characteristics andadvantages of the present disclosure will become more apparent from thefollowing detailed description of the example embodiments with referenceto the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a motor according to an exampleembodiment of the present disclosure.

FIG. 2 is a plan view of a laminate member of a core piece according toan example embodiment of the present disclosure.

FIG. 3 is a plan view of laminate members of laminated core piecesaccording to an example embodiment of the present disclosure.

FIG. 4 is a plan view of annularly connected core pieces according to anexample embodiment of the present disclosure.

FIG. 5 is an enlarged view of a connection portion of adjacent corepieces according to an example embodiment of the present disclosure.

FIG. 6 is a view showing an area, in which core back portions ofadjacent core pieces overlap each other in a lamination directionaccording to an example embodiment of the present disclosure.

FIG. 7 is a cross-sectional view of a connection portion of adjacentcore pieces according to an example embodiment of the presentdisclosure.

FIG. 8 is a plan view of a core piece according to a modified exampleembodiment of the present disclosure.

FIG. 9 is a cross-sectional view of a connection portion of core piecesaccording to a modified example embodiment of the present disclosure.

FIG. 10 is a flowchart showing a process of manufacturing a statoraccording to an example embodiment of the present disclosure.

FIG. 11 is a view showing a laminate member formed on a plate memberused in a process of manufacturing a stator according to an exampleembodiment of the present disclosure.

FIG. 12 is view showing laminate members of core pieces in the processof manufacturing a stator according to an example embodiment of thepresent disclosure.

FIG. 13 is a view showing a divided stator having a coil formed bywinding a conductive wire around teeth of a core piece in the process ofmanufacturing a stator according to an example embodiment of the presentdisclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, example embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings. Theembodiments described below are only exemplary examples of the presentinvention, but the technical scope is not limited thereby. Further, thesame reference numerals may be assigned to the same components, and thedescriptions thereof may be omitted.

The exemplary embodiments of the present invention relate to aconfiguration of a stator (also referred to as a “stator core”) used ina motor and a method of manufacturing the stator. In the description,the term “core piece” refers to an element including a tooth portionaround which a conductive wire is not wound and a core back portionhaving an annular shape in a connected state. The term “core” refers toa group of a plurality of annularly connected core pieces. The term“divided stator” refers to a core piece around which the conductive wireis wound. The term “stator” refers to a group of a plurality of dividedstators in an annularly connected state. Further, each layer of the corepiece, which defines the core piece by being laminated, refers to a“laminate member.” Further, the term “laminate member” does notnecessarily refer to only a layer of the member of the core piece, butmay include a plurality of layers of the members having the same orsimilar shapes and consecutively laminated.

Further, for convenience of description in the specification, inlaminate members laminated in a manufacturing process, a direction inwhich the laminate members are laminated refers to an “upper side” or an“upper direction,” and a direction in which laminate members, which arealready laminated, are positioned refers to a “lower side” or a “lowerdirection.” In most cases, the lower side opposing the upper side ispositioned on a lower side in a gravity direction. Further, a directionin which the laminate members composing the core piece are laminatedrefers to a “lamination direction.” In the following description, thelamination direction is parallel to a central axis of rotation of themotor, but the lamination direction and the central axis are notnecessarily parallel to each other.

FIG. 1 is a cross-sectional view of a motor 80 of one embodiment of thepresent invention. As shown in FIG. 1, the motor 80 preferably includesa shaft 81, a rotor 82, a stator 83, a housing 84, a bearing holder 85,a first bearing 86, a second bearing 87, an insulator 88, a coil-drawingline 89, a coil 90, and the like. The shaft 81 and the rotor 82 areintegrated with each other by, for example, the shaft 81 being press fitthrough the rotor 82. The shaft 81 has a cylindrical shape having acenter that is a central axis extending in one direction. The rotor 82is positioned at a middle of the shaft 81. The rotor 82 is rotatableabout the stator 83. The stator 83 is disposed to surround the rotor 82in an axial direction. The stator 83 includes the coil 90 which ispreferably formed by winding a conductive wire around the core of thestator 83. The housing 84 is engaged with an outer circumferentialsurface of the stator 83 and accommodates the shaft 81, the rotor 82,the stator 83, the bearing holder 85, the first bearing 86, the secondbearing 87, the insulator 88, the coil-drawing line 89, and the coil 90which compose the motor 80. The bearing holder 85 supports the secondbearing 87. The bearing holder 85 is engaged with the housing 84. Thefirst bearing 86 is preferably disposed at a lower portion of thehousing 84 and supports one side of the shaft 81. The second bearing 87supports the other side of the shaft 81. The insulator 88 is disposedbetween the stator 83 and a conductive wire of the coil 90 to insulatethe stator 83 and the conductive wire of the coil 90.

FIG. 2 is a plan view of one laminate member 10 a of a core piece 10which defines the stator 83. FIG. 3 is a plan view of the laminated corepieces 10. FIG. 4 is a plan view of a core 1 in a state in which thecore pieces 10 are annularly connected.

As shown in FIG. 4, a center point of a circle of an outercircumferential surface or an inner circumferential surface defined bythe core 1 is C1. Straight lines A1, A2, and A3 shown in FIGS. 2 and 3each are lines extending in a radial direction through the center pointC1. An inner angle between the straight line A1 and the straight line A2and an inner angle between the straight line A1 and the straight line A3are preferably about 15°, for example. An inner angle between toothportions 40 of adjacent core pieces 10 is preferably about 30°, forexample. An inner angle between the tooth portions 40 of the adjacentcore pieces 10, an inner angle between the straight lines A1 and A2, andan inner angle between the straight lines A1 and A3 vary according tothe number of core pieces 10 forming the core 1. The core 1 according tothe embodiment of the present invention preferably includes the twelvecore pieces 10, and thus, as described above, each of the inner anglesbetween the tooth portions 40 of the adjacent core pieces 10 ispreferably about 30°. Further, the number of core pieces 10 of the core1 may be arbitrarily changed as desired.

As shown in FIG. 2, the laminate member 10 a of the core piece 10includes the tooth portion 40 and the core back portion 20. The corepiece 10 is formed by laminating the plurality of laminate members 10 awith a predetermined thickness. The tooth portion 40 is linearlysymmetrical with respect to the straight line A1 passing through thecenter point C1. The tooth portion 40 has a shape in which an end on aninner side in a radial direction extends in a circumferential direction,and has an inner circumferential surface 41 on the inner side in theradial direction.

As shown in FIG. 3, one laminate member and another laminate member ofthe core piece 10 are laminated so that the tooth portion 40 does notprotrude. Since circumferential lengths of one circumferential end ofone laminate member and another circumferential end of another laminatemember are different from each other, one side protrudes from anotherside.

The core back portion 20 is an element defining an annular portion ofthe core 1. The core back portion 20 is preferably connected with aradially outer side of the tooth portion 40 and has a shape extending ina circumferential direction.

The core back portion 20 includes a circular arc-shaped protrusion 21and a radially straight portion 22 formed at one end thereof in thecircumferential direction. The radially straight portion 22 has a shapeof a straight line extending in a radial direction through the centerpoint C1. The radially straight portion 22 protrudes outward of thestraight line A1 in a circumferential direction. The circular arc-shapedprotrusion 21 has a shape of protruding circumferentially outward of aradially straight line passing through the center point C1 and theradially straight portion 22. The circular arc-shaped protrusion 21preferably has a circular arc shape partially overlapping a circlehaving a center that is an intersection point C2 between the straightline A2 and an outer circumferential recess 26 b of the core backportion 20. An end on a circumferential inner side of the circulararc-shaped protrusion 21 is connected with an end on the circumferentialouter side of the radially straight portion 22, and the circulararc-shaped protrusion 21 and the circumferential end of the radiallystraight portion 22 become one circumferential end of the core backportion 20.

Further, the circular arc-shaped protrusion 21 may not necessarily havea circular arc shape if so desired. For example, the core back portion20 may be a protrusion with an arc shape of an ellipse or a gentlycurved protrusion instead of the circular arc-shaped protrusion 21. Buta portion corresponding to the circular arc-shaped protrusion 21 of oneend of the core back portion 20 is in contact with a contact portion 23of an adjacent core piece at one point.

The core back portion 20 includes the contact portion 23 and a radiallystraight portion 24 provided at the other end thereof in thecircumferential direction. Like the radially straight portion 22, theradially straight portion 24 preferably has a shape extending in aradial direction through the center point C1. Unlike the radiallystraight portion 22, the radially straight portion 24 has a shape ofbeing recessed circumferentially inward of the straight line A3. Thecontact portion 23 preferably has a straight shape with an inclinedsurface recessed circumferentially inward of the radially straightportion 24. An inner angle between the radially straight portion 22 andthe contact portion 23 is preferably about 135°. An end on acircumferential inner side of the contact portion 23 is connected withan end on a circumferential outer side of the radially straight portion24, and the contact portion 23 and one circumferential end of theradially straight portion 24 become the other circumferential end of thecore back portion 20.

FIG. 5 is an enlarged view of a connection portion of laminate members10 a and 11 a of the core pieces 10 and 11 adjacent to each other. Asshown in FIG. 5, an inner angle P2 between the radially straight portion24 and the contact portion 23 is preferably about 135°.

Further, the contact portion 23 may not necessarily have a straight lineshape. For example, the contact portion 23 may be a shape of a circulararc-shaped protrusion or recess or a curved part. But a portioncorresponding to the contact portion 23 of the other end of the coreback portion 20 is in contact with the circular arc-shaped protrusion 21of the adjacent core piece at one point. The contact portion 23 refersto a linear recess as a representation corresponding to the circulararc-shaped protrusion.

As shown in FIG. 5, one end of the laminate member 10 a of the corepiece 10 is preferably in contact with the other end of the laminatemember 11 a of the adjacent core piece 11. Specifically, the circulararc-shaped protrusion 21 of the core piece 10 and the contact portion 23of the core piece 11 are in contact with each other at one contact pointP1. The radially straight portion 22 of the core piece 10 and theradially straight portion 24 of the core piece 11 are spaced apart fromeach other. But the radially straight portion 22 of the core piece 10and the radially straight portion 24 of the core piece 11 are notnecessarily spaced apart from each other and may be in contact with eachother.

As described above, in the core piece 10 and the core piece 11 which areadjacent to each other, the circular arc-shaped protrusion 21 of thelaminate member 10 a of the core piece 10 and the contact portion 23 ofthe laminate member 11 a of the core piece 11 are in contact with eachother at one point. When the core piece 10 rotates outward of the radialdirection with respect to the core piece 11, the radially straightportion 22 and the radially straight portion 24 are not in contact witheach other, but the circular arc-shaped protrusion 21 and the contactportion 23 are in contact with each other at one point. Even when thecore piece 11 and the core piece 10 relatively rotate, the core piece 10and the core piece 11 are in contact with each other at one point, andthus a frictional resistance between the core piece and the core piece11 decreases. Therefore, compared to a configuration in which corepieces adjacent to each other are in surface contact with each other orin contact with each other at a plurality of points as in theconventional art, the core pieces can rotate while connected with eachother.

Further, when the core piece 10 rotates with respect to the core piece11, a center of rotation is a center C2 of a circular arc of thecircular arc-shaped protrusion 21. In the laminate members of the corepiece 10, since the center C2 coincides with a lamination direction, thecore piece 10 may smoothly rotate about the center C2 as an axis.

Further, in the laminate members 10 a and 11 a of the core pieces 10 and11, an inner angle between the radially straight portion 24 and thecontact portion 23 is 135°, and thus the core piece 10 may rotate withina wide range when rotating with respect to the core piece 11 while beingin contact with the core piece 11 at one point. Further, the inner angleP2 is not necessarily limited to preferably about 135° and may bechanged within a range of about 130° to about 140°. Even when the innerangle P2 is an arbitrary angle in a range of about 130° to about 140°,the core pieces can be rotated in a sufficiently wide range while beingin contact with each other at one point.

An outer circumferential surface of the core back portion 20 is engagedwith a housing (not shown) when a motor is assembled. The core backportion 20 includes a central recess 29, outer circumferential surfaces25 a and 25 b, and outer circumferential recesses 26 a and 26 b providedat an outer circumferential portion thereof.

The central recess 29 is incised inward in the radial direction at aposition at which an outer circumferential surface of the core backportion 20 and the straight line A1 intersect with each other. Thecentral recess 29 extends in a groove shape in a vertical direction inwhich the laminate members are laminated.

Each of the outer circumferential surfaces 25 a and 25 b preferably hasa circular arc shape including a center that is the center point C1. Theouter circumferential surfaces 25 a and 25 b are connected with bothcircumferential sides of the central recess 29. The outercircumferential surfaces 25 a and 25 b are portions which are in contactwith the inner circumferential surface of the housing while the statorincluding the core 1 around which the conductive wire is wound isengaged with an inner side of the housing.

The outer circumferential recesses 26 a and 26 b are connected withcircumferential end sides on the outer circumferential surfaces 25 a and25 b. The outer circumferential recesses 26 a and 26 b are recessed fromthe outer circumferential surfaces 25 a and 25 b inward in a radialdirection. The outer circumferential recesses 26 a and 26 b include acircular arc shape having a smaller diameter than that of the outercircumferential surfaces 25 a and 25 b and having the center point C1the same as that of the outer circumferential surfaces 25 a and 25 b.When the stator is fitted to an inner side of the housing, the outercircumferential recesses 26 a and 26 b are not in contact with an innercircumferential surface of the housing, and thus gaps are definedbetween the inner circumferential surface of the housing and the outercircumferential recesses 26 a and 26 b.

The outer circumferential surface of the core back portion 20 of thecore piece 10 is preferably engaged with the housing as a stator, asdescribed above, the outer circumferential surfaces 25 a and 25 b are incontact with an inner circumferential surface of the housing, and thecentral recess 29 and the outer circumferential recesses 26 a and 26 bare not in contact with the inner circumferential surface of thehousing. Therefore, accuracy of a size of the outer circumferentialsurface of the core back portion 20 increases. Further, the core backportion 20 may not necessarily have the outer circumferential recesses26 a and 26 b. When the core back portion 20 has a shape having theouter circumferential recesses 26 a and 26 b, dimensions of the outercircumferential surfaces 25 a and 25 b more effectively increase.

The core back portion 20 preferably includes inner circumferentialsurfaces 27 a and 27 b and inner circumferential recesses 28 a and 28 bprovided on an inner circumferential surface thereof. The innercircumferential surfaces 27 a and 27 b have a circular arc shape havinga center that is the center point C1. The inner circumferential surfaces27 a and 27 b are connected with both circumferential sides of the toothportion 40. The inner circumferential recesses 28 a and 28 b areconnected with circumferential end sides of the inner circumferentialsurfaces 27 a and 27 b. The inner circumferential recesses 28 a and 28 bare recessed from the inner circumferential surfaces 27 a and 27 boutward in the radial direction. The inner circumferential recesses 28 aand 28 b preferably include a circular arc shape having an innerdiameter smaller than that of the inner circumferential surfaces 27 aand 27 b having the center that is the center point C1 the same orsubstantially the same as that of the inner circumferential surfaces 27a and 27 b.

As shown in FIG. 3, when the core piece 10 including a plurality oflaminate members which are laminated is viewed from above, sincepositions of both circumferential ends of the core back portion 20 aredifferent from each other among the laminate members, the laminatemember disposed on a lower side is partially shown. When viewed fromabove, a circular arc-shaped protrusion 121, a radially straight portion122, an outer circumferential recess 126 a, and an inner circumferentialrecess 128 a of the laminate member disposed below the laminate memberdisposed on the top are shown at the contact portion 23, which isdefined short in a circumferential direction of the core back portion20, and a circumferential outer side of the radially straight portion24. The circular arc-shaped protrusion 121, the radially straightportion 122, the outer circumferential recess 126 a, and the innercircumferential recess 128 a of the laminate members of the core piece10 overlap an adjacent core piece in a lamination direction.

FIG. 6 is a view showing the core back portions 20 of the core pieces 10and 11 adjacent to each other overlap each other in a laminationdirection, and particularly, a view showing an overlapping area. Acircular arc-shaped protrusion 221, a radially straight portion 222, anouter circumferential recess 226 a, and an inner circumferential recess228 a of the laminate member of the core piece 11 are preferablylaminated on the circular arc-shaped protrusion 121, the radiallystraight portion 122, the outer circumferential recess 126 a, and theinner circumferential recess 128 a of the laminate member of the corepiece 10. The laminate member of the core piece 10 is disposed under thelaminate member of the core piece 11. As shown in FIG. 6 with inclinedlines, the core piece 10 and the core piece 11 overlap in an area R. Aboundary of the area R is determined by the circular arc-shapedprotrusion 221, the radially straight portion 222, the outercircumferential recess 226 a, and the inner circumferential recess 228a, which are laminate members of the core piece 11 positioned on anupper side, and the circular arc-shaped protrusion 121, the radiallystraight portion 222, the outer circumferential recess 226 a, and theinner circumferential recess 228 a, which are laminate members of thecore piece 10 positioned on a lower side. But the outer circumferentialrecess 226 a and the inner circumferential recess 228 a, the outercircumferential recess 226 a, and the inner circumferential recess 228 apreferably overlap each other in the lamination direction.

For example, an area of the area R is greater than an area of acircumferentially cross-sectional area of the core back portion 20 at aposition of the straight line A3. Further, the cross-section of the coreback portion 20 is calculated by multiplying a circumferential length ofthe core back portion 20 and a thickness of the laminate member. Thereason why the area R is formed as described above is as follows.

One circumferential end of each of the laminate members of the corepiece 10 is in contact with the other circumferential end of each of thelaminate members of the core piece 11 at one point. For this reason, ascompared with when one circumferential end of the core piece 10 is insurface contact with the other circumferential end of the core piece 11,a magnetic path defined by circumferential ends of the core pieces 10and 11 so that an amount of magnetic flux flowing therein is narrow.Therefore, the area greater than or equal to the magnetic path which isnarrowed due to the area R is able to be secured. Further, since theradially straight portion 22 and the radially straight portion 24 arenot in contact with each other in a circumferential direction in anassembled state, the magnetic path is not provided at a position atwhich the radially straight portion 22 and the radially straight portion24 are in contact with each other.

Even when one circumferential end of the laminate member of the corepiece 10 is not in contact with the other circumferential end of thelaminate member of the core piece 11 adjacent thereto, is in surfacecontact therewith, or is in contact with at a plurality of points, themagnetic path is defined in the area R, and thus the magnetic propertyis improved.

Further, it is preferable that the area R be less than or equal to about5 times the circumferential cross-sectional area of the core backportion 20. Therefore, an area in which the core back portions 20 of theadjacent core piece 10 overlap in the lamination direction issufficiently secured, and thus a sufficient magnetic path is able to besecured. Further, because a frictional resistance is prevented frombeing excessively generated in the lamination direction of the core backportion 20 of the adjacent core piece 10, the adjacent core pieces areable to rotate in a manufacturing process.

FIG. 7 is a cross-sectional view of the connection portion of the corepieces 10 and 11 adjacent to each other. As shown in FIG. 7, the corepiece 10 is preferably defined by laminate members 10 a to 10 d whichare laminated. The core piece 11 is preferably defined by laminatemembers 11 a to 11 d which are laminated. Ends of the core piece 10 andthe core piece 11 face each other and preferably have uneven parts. Theuneven part of the end of the core piece 10 is engaged and connectedwith the uneven portion of the end of the core piece 11.

An end 32 a of the radially straight portion 22 or the circulararc-shaped protrusion 21 is preferably provided at a circumferential endof the laminate member 10 a of the core piece 10. An end 35 a of theradially straight portion 24 or the contact portion 23 is preferablydefined at a circumferential end of the laminate member 11 a of the corepiece 11 to face the end 32 a. An upper recess 31 a, which is morerecessed from an upper surface of a circumferential inner side of thecore piece 10, is provided at an upper side of the circumferential innerside of the end 32 a. A lower surface 34 a is positioned under thecircumferential inner side of the end 32 a. An inclination 33 a isprovided between the end 32 a and the lower surface 34 a. When viewedfrom above, the inclination 33 a is positioned at the circulararc-shaped protrusion 121 protruding from the upper laminate member inthe circumferential direction, the radially straight portion 122, theouter circumferential recess 126 a, and the inner circumferential recess128 a (see FIG. 6). The inclination 33 a is preferably formed by achamfering process in the manufacturing process, for example.

The laminate member of the core piece 10 is preferably formed bypunching a plate member in the manufacturing process, for example. Inthis case, a burr protruding downward is formed on a lower surface ofthe laminate members. Since the burr causes interference in accuratelamination when the laminate members are laminated, the above-describedchamfering is performed. Further, the inclination 33 a is formed by thechamfering, and thus the core pieces are able to be smoothly rotated.Further, the lower side of the core piece 10 may be formed to have acurved shape instead of the inclination 33 a.

A gap 61 may be defined between a lower surface 34 a of the laminatemember 10 a and an upper recess 31 b of the laminate member lib in alamination direction. Similarly, a gap 62 is defined between thelaminate member lib and the laminate members 10 c, and a gap 63 isprovided between the laminate member 10 c and the laminate member 11 d.The gaps 61, 62, and 63 preferably have a distance of greater than orequal to about 5 μm to less than or equal to about 20 μm so thatmagnetic paths are appropriately defined. Further, in order to form themore appropriate magnetic path, the gaps preferably have a distance ofgreater than or equal to about 5 μm to less than or equal to about 10μm, for example.

The gaps 61, 62, and 63 preferably have long and short distances ratherthan the same distance. For example, in the present embodiment, the gaps61 and 63 have a distance of about 5 μm, and the gap 62 has a distanceof about 10 μm. An effective magnetic path is secured at a portion atwhich a distance in the lamination direction of the laminated portion ofthe adjacent core pieces is short, and a frictional resistance decreasesat a portion at which a distance in the lamination direction is long.Therefore, when the effective magnetic path is provided, the magneticproperty is secured, and the core pieces are able to be easily rotatedin the manufacturing process.

Further, a lower recess is preferably provided on a lower side of acircumferential inner side of the circumferential end 32 a of thelaminate member 10 a, similar to the upper recess 31 a. Further, thelower recess may be provided on the laminate member 10 a instead of theupper recess 31 a.

A stator, a core, and a core piece of the present invention are notlimited to the above-described embodiment, and various forms made basedon the embodiment may be included. For example, the stator, the core,and the core piece of the present invention may be components having themodified embodiments described below. Further, the same components asthose in the above-described embodiment will be designated with the samename or numeral references, and the description thereof may be omitted.

FIG. 8 is a plan view of laminate members 12 a defining a core piece 12as a modified embodiment according to the present invention. As shown inFIG. 8, the shapes of both circumferential ends of the laminate member12 a of the modification are different from those of the laminate member10 a (see FIG. 2) according to the above-describe preferred embodimentof the present invention.

Specifically, the laminate member 12 a has a circular arc-shapedprotrusion 21 a provided at one circumferential end of the core backportion 20 a thereof. The laminate members 12 a has a contact portion 23a defined at the other circumferential end of the core back portion 20a. The laminate member 12 a of the modification does not have radiallystraight portions defined at both ends thereof.

Even in the case of this configuration, ends in a circumferentialdirection of the adjacent core pieces are in contact with each other atone point, and the same effect as that of the above-described embodimentis obtained. The core piece 12 of the modification is used, and thus thelaminate members of the core piece are able to be easily manufactured.

However, as described in the above-described embodiment, when thelaminate member includes the radially straight paths 22 and 24, and onecore piece is rotated in a direction in which an inner side in theradial direction gets close to the other core piece, the radiallystraight paths 22 and 24 come into contact with each other. Therefore,one core piece is able to prevented from rotating in a direction inwhich the radially inner side gets close to the other core piece.

FIG. 9 is a cross-sectional view of a connection portion of core pieces13 and 14 in a modified embodiment according to the present invention.As shown in FIG. 9, when compared to the core pieces 10 and 11 (see FIG.7) according to the above-described embodiment, the core pieces 13 and14 of the modification preferably have a different lamination shape inthe vicinity of circumferential ends thereof.

Specifically, a lower protrusion 36 a additionally protruding downwardfrom a lower surface 34 a is preferably defined on a lower side of acircumferential inner side of the end 32 a of a laminate member 13 a ofthe core piece 13. A second upper recess 37 b, which overlaps thelamination member 13 a in the lamination direction and is more recessedthan the upper recess 31 b, is provided at an upper side of acircumferential inner side of the end 32 b of a laminate member 14 b ofthe core piece 14. The lower protrusion 36 a and the second upper recess37 b face each other in a lamination direction and are engaged with eachother. Therefore, uneven portions engaged with each other are defined ata portion at which laminate members of the adjacent core pieces 13 and14 overlap each other in the lamination direction, and thus the corepiece 13 and the core piece 14 can be prevented from being separated.

Next, a method of manufacturing a stator of an example embodiment of thepresent invention will be described with referent to FIGS. 10 to 13.Further, although the laminate members are arranged in a transversedirection of a plate member corresponding to number of annularlyconnected cores in practice, only a portion of them are shown in FIGS.11 to 13, and the others are omitted for the sake of simplicity.Hereinafter, in a plane which is horizontal to a gravity direction, adirection horizontal to a transfer direction of the plate member refersto a “transverse direction.”

FIG. 10 is a flowchart showing a process of manufacturing a statoraccording to an example embodiment of the present invention. In theprocess of manufacturing the stator, a process of separating a laminatemember from a plate member, which is a base material, (S100) isperformed first. When the laminate member is separated, the separatedlaminate member is laminated on the laminate member (S110).

FIG. 11 is a view showing laminate members 101 a, 101 b, 101 c, 101 d,102 a, 102 b, 102 c, 102 d, 103 a, 103 b, 103 c, 103 d, 104 a, 104 b,104 c, and 104 d of core pieces provided on a plate member 2. Thelaminate members 101 a, 101 b, 101 c, and 104 d are arranged in eachlamination layer. The laminate members 101 a, 101 b, 101 c, and 104 dare arranged in a first layer, the laminate members 102 a, 102 b, 102 c,and 102 d are arranged in a second layer, the laminate members 103 a,103 b, 103 c, and 103 d are arranged in a third layer, and the laminatemembers 104 a, 104 b, 104 c, and 104 d are arranged in a fourth layer,and thus the core piece is formed. In the process of separating thelaminate members, the laminate members in the same layer aresimultaneously or sequentially separated.

When all of the laminate members are not laminated (N of S120), theplate member 2 is transferred in a transfer direction S (see FIG. 11),then the laminate members to be laminated are transferred to aseparation position (S130). For example, before separation of thelaminate members 102 a, 102 b, 102 c, and 102 d in the second layer isperformed, the laminate members 102 a, 102 b, 102 c, and 102 d formed onthe plate member 2 are positioned right above the separated laminatemembers 101 a, 101 b, 101 c, and 101 d in the first layer. Further, aseparation of the laminate members 102 a, 102 b, 102 c, and is performed(S100) so that the laminate members 102 a, 102 b, 102 c, and 102 d arelaminated on the laminate members 101 a, 101 b, 101 c, and 101 d.

FIG. 12 is a view showing core pieces in which laminate members arelaminated in a process of manufacturing a stator. When all of thelaminate members are laminated (Y of S120), as shown in FIG. 12, corepieces 15 a, 15 b, 15 c, and 15 d in which the laminate members arelaminated are arranged in a transverse direction. In this state,conductive wires are wound around tooth portions 40 of the core pieces15 a, 15 b, 15 c, and 15 d, and thus a coil 70 is formed (S140). Whenthe conductive wires are wound around the tooth portions 40 of the corepieces 15 a to 15 d, the core pieces 15 a, 15 b, 15 c, and 15 d may berotated in a direction in which tooth portions 40 of the adjacent corepieces are spaced apart from each other, and thus a wide space providedaround the tooth portions 40 allows the conductive wires to be easilywound around the tooth portion 40. In this case, the circular arc-shapedprotrusion 21 and the contact portion 23 of the adjacent core pieces arein contact with each other at one point, and the core pieces are rotatedabout a center C2 while changing a contact position. FIG. 13 is a viewshowing divided stators on which a coil 70 is formed by winding aconductive wire around tooth portions 40 of core pieces 15 a, 15 b, 15c, and 15 d. When the conductive wires are wound around the toothportions 40, the divided stators of the core pieces 15 a to 15 d aroundwhich the conductive wires are wound are rotated, and the core backportions 20 are annularly connected (S150). Thus, the stator having thecore 1, on which the conductive wire is wound, shown in FIG. 4 isformed.

Further, the plate member 2 used in a manufacturing configuration maynot be necessarily one plate member but may be two or more plate membersif so desired.

As such, the embodiments and the modifications of the present inventionhave been described in detail. The above-descriptions are only exemplaryand the present invention is not limited thereto and may be widelyinterpreted within the range in which those skilled in the artunderstand. For example, the above embodiments and each modification maybe implemented in combination with each other.

Features of the above-described preferred embodiments and themodifications thereof may be combined appropriately as long as noconflict arises.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A stator, comprising: an annular core including acenter that is a vertically extending central axis; and a conductivewire that is wound around the core; wherein the core includes corepieces in which at least a first laminate member and a second laminatemember are respectively laminated; the first laminate member includes afirst tooth portion extending in a radial direction and a first coreback portion connected to a radially outer side of the first toothportion and extending in a circumferential direction; the secondlaminate member includes a second tooth portion extending in the radialdirection and a second core back portion connected to a radially outerside of the second tooth portion and extending in the circumferentialdirection; the first core back portion includes a first protrusionlocated on one side thereof in the circumferential direction and a firstrecess located on another side thereof in the circumferential direction;the second core back portion includes a second recess located on oneside thereof in the circumferential direction and a second protrusionlocated on another side thereof in the circumferential direction; thefirst protrusion of one of the core pieces and the second protrusion ofanother one of the core nieces adjacent thereto overlay in a laminationdirection of the annular core; a total area of a region in which the oneof the core pieces opposes the another one of the core pieces in thelamination direction is greater than, but also less than about 5 timesas large as, a circumferential cross sectional area of a radially outerside of the first tooth portion and the second tooth portion of the oneof the core pieces.
 2. The stator according to claim 1, wherein a thirdlaminate member is further laminated on the core piece; the thirdlaminate member includes a third tooth portion extending in the radialdirection and a third core back portion extending in a circular arcshape from a radially outer position of the third tooth portion; thethird core back portion includes a third protrusion on one side thereofin the circumferential direction and a third recess on another sidethereof in the circumferential direction; and a distance between thefirst core back portion and the second core back portion of the corepiece adjacent thereto in the lamination direction is different from adistance between the second core back portion and the third core backportion of the core piece adjacent thereto in the lamination direction.3. The stator according to claim 1, wherein a distance between the firstcore back portion and the second core back portion of the core pieceadjacent thereto in the lamination direction is greater than or equal toabout 5 μm and less than or equal to about 20 μm.
 4. The statoraccording to claim 1, wherein the first protrusion is in contact withthe another one of the core pieces at one point.
 5. The stator accordingto claim 4, wherein the second protrusion is in contact with the one ofthe core pieces at one point.
 6. The stator according to claim 5,wherein each of the first protrusion and the second protrusion includesa circular arc shape.
 7. The stator according to claim 6, wherein thefirst protrusion includes a circular arc shape with a center that is aposition at which a bisector between a radial center line of the firsttooth portion and a radial center line of the first tooth portion of theanother one of the core pieces intersects with an outer circumferentialsurface of the first core back portion; and the second protrusionincludes a circular arc shape with a center that is a position at whicha bisector between a radial center line of the second tooth portion anda radial center line of the second tooth portion of the core pieceadjacent thereto intersects with an outer circumferential surface of thesecond core back portion.
 8. The stator according to claim 5, whereinthe first core back portion further includes a first contact portionlocated at the another side thereof in the circumferential direction;the second core back portion further includes a second contact portionlocated at one side thereof in the circumferential direction; the firstprotrusion is in contact with the first contact portion adjacent theretoat one point; and the second protrusion is in contact with the secondcontact portion adjacent thereto at one point.
 9. The stator accordingto claim 8, wherein each of the first contact portion and the secondcontact portion has a straight line shape.
 10. The stator according toclaim 9, wherein the first core back portion includes a first radiallystraight portion extending in the radial direction on the one sidethereof in the circumferential direction, and a second radially straightportion extending in the radial direction on the another side thereof inthe circumferential direction; and the second core back portion includesa third radially straight portion extending in the radial direction onthe one side thereof in the circumferential direction, and a fourthradially straight portion extending in the radial direction on theanother side thereof in the circumferential direction.
 11. The statoraccording to claim 10, wherein the first contact portion includes aninclined surface with an inclination greater than or equal to about 130°and less than or equal to about 140° with respect to the first radiallystraight portion; and the second contact portion includes an inclinedsurface with an inclination greater than or equal to about 130° and lessthan or equal to about 140° with respect to the third radially straightportion.
 12. The stator according to claim 1, wherein the first coreback portion includes an inclined or curved shape on a lower side of oneside thereof in the circumferential direction or the other side thereofin the circumferential direction which overlaps the core piece adjacentthereto; and the second core back portion includes an inclined or curvedshape on a lower side of the other side thereof in the circumferentialdirection or one side thereof in the circumferential direction whichoverlaps the core piece adjacent thereto.
 13. The stator according toclaim 1, wherein the first protrusion of the one of the core piecesincludes a fourth protrusion protruding in the lamination direction or afourth recess recessed in the lamination direction; the secondprotrusion of the another one of the core pieces includes a fifth recessrecessed in the lamination direction or a fifth protrusion protruding inthe lamination direction; and the fourth protrusion and the fifth recessor the fourth recess and the fifth protrusion are engaged with eachother.
 14. The stator according to claim 1, wherein the first core backportion includes a first central recess incised inward in the radialdirection at a position at which an outer circumferential surface and anextended line of the center line of the first tooth portion intersecteach other, and the second core back portion includes a second centralrecess incised inward in the radial direction at a position at which anouter circumferential surface and an extended line of the center line ofthe second tooth portion intersect each other.
 15. A motor comprisingthe stator according to claim 1.